Device, method, and system for monitoring the delivery of fluids through a drip chamber

ABSTRACT

A device, method, and system are provided for monitoring the delivery of fluids through a drip chamber. The device includes an electromagnetic radiation (EMR) source and an EMR detector. A device body is employed to position the source and detector about the drip chamber so that the source and detector define an optical path across the drip chamber. A processor device is employed to detect fluid drops from differences between detector signal values separated by a lag time. The flow rate is determined from a drip factor and the detection of multiple drops. In the context of delivering intravenous (IV) fluids, a battery powered handheld monitoring device that includes the source, detector, device body, and processor device may be affixed to a drip chamber included in an infusion set. The device includes a user interface, including buttons, a display, and an audio speaker, for the input and output of information.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application, which was filed on Feb.24, 2014, claims the benefit for U.S. Provisional Patent Application No.61/769,109, filed Feb. 25, 2013, which provisional patent application isincorporated herein by reference in its entirety.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

The present disclosure relates, generally, to the delivery ofintravenous fluids, more specifically to the monitoring of the rate atwhich fluids are delivered intravenously to a subject, and themonitoring may affect control of this rate. Provided herein are devices,methods, and systems for use in the real time monitoring of a fluid flowrate and an accumulated total volume delivered through a drip chamber.

2. Description of the Related Art

Many scenarios require the administration of a prescribed volume offluid, delivered over a prescribed length of time and at a relativelysteady rate. One context where this is routinely required is thedelivery of pharmaceuticals, nutrients, and other fluids in a healthcaresetting. For instance, a clinical treatment may require a prescribeddosage of a pharmaceutical delivered intravenously (IV) to a patientover a multi-hour time period and at an approximately constant rate.

Gravity fed infusion sets are routinely employed for such applications.Typical infusion sets allow a user to manually adjust the delivery rateof the fluid flow by visually inspecting individual drops of the fluidfalling within a drip chamber and adjusting a roller clamp accordingly.If the user desires a faster flow rate, the roller clamp is adjusted inone direction, resulting in a greater drop flux in the drip chamber. Ifthe roller clamp is open too wide, the flux of individual drops becomesa continuous stream of fluid.

If the user desires a slower flow rate, the user adjusts the rollerclamp in another direction, resulting in a lesser flux in the dripchamber. If the roller clamp is fully closed, fluid ceases to flowthrough the infusion set. Typically, the drip chamber is at leastpartially transparent to light, allowing for visual inspection of thefluid drop flux.

It is difficult to estimate a fluid flow rate by visually inspectingfalling drops. Also, without continual visual inspection, a user such asa caregiver or patient may not notice if the flow rate becomes unstableor ceases to flow. Such instabilities may occur if the infusion setbecomes clogged, a fluid source, such as an IV bag, becomes depleted, orthe infusion set is no longer parallel with the gravitational field. Forinstance, if a patient inadvertently knocks over a structure that issupporting the infusion set, the flow of fluid may cease or becomeunstable. Furthermore, a user may determine a total accumulated dosedelivered to the patient by noting graduations on an IV bag. However,again the user must manually perform cumbersome inspections that areprone to human induced error.

The efficacy of a clinical treatment may require that a precise totaldose of the fluids or pharmaceutical is delivered to the patient at arelatively stable rate over the prescribed time period. It is with theseand other concerns that the following disclosure is offered.

SUMMARY OF THE DISCLOSURE

The present disclosure provides at least devices, methods, and systemsfor providing real time monitoring of a fluid flow rate and anaccumulated total volume through a drip chamber.

Various embodiments of presently disclosed fluid flow rate monitoringdevices include a source enabled to emit electromagnetic radiation(EMR), a detector enabled to generate a detector signal, a device bodyconfigured and arranged to position the source and the detector about atleast one outer surface of the drip chamber such that the source and thedetector define an optical path across the drip chamber, wherein fluidbetween the source and the detector inhibits EMR travelling along theoptical path; a device body configured and arranged to position thesource and the detector about at least one outer surface of the dripchamber such that the source and the detector define an optical pathacross the drip chamber, wherein fluid between the source and thedetector inhibits EMR travelling along the optical path; and a processordevice that executes instructions that perform actions. The actionsinclude detecting a fluid drop based on at least a difference between aplurality of detector signal values temporally separated by apredetermined lag time and determining the flow rate of fluid based onat least a predetermined drip factor and detecting a plurality of fluiddrops.

In some embodiments, detecting the fluid drop may be further based on acomparison of a plurality of temporally ordered difference values,wherein each of the plurality of difference values correspond todifferences in the plurality of detector signals that are temporallyseparated by the lag time. Additionally, the actions may further includevetoing a detection of a second fluid drop when a temporal differencebetween the detection of the second fluid drop and a detection of afirst fluid drop is less than a predetermined lockout time.

In at least one of the various embodiments, detecting the fluid drop mayfurther include generating a drop waveform based on detector signalvalues sampled at a plurality of temporally ordered times, wherein thedrop waveform is modulated by the fluid drop, generating a lag timedifference waveform based on at least the lag time and a plurality ofdifferences of the drop waveform corresponding to different times, anddetecting the fluid drop based on at least a signal included in the lagtime difference waveform.

In some embodiments, the source may be a light emitting diode (LED). Insome embodiments, the detector may be a photodiode. In at least one ofthe various embodiments, the source may be further enabled to emit EMRwithin a wavelength window, wherein wavelengths within the wavelengthwindow are longer than visible light wavelengths and a sensitivity ofthe detector is greater for at least a portion of the wavelengths withinthe wavelength window than for visible light wavelengths.

In some embodiments, the actions may further include detecting a firstfluid drop at a first detection time, adding the first detection time toa drop history buffer, wherein the drop history buffer includes at leasta plurality of other detection times and each of the other detectiontimes corresponds to a previously detected fluid drop, removing at leastone of the other detection times from the drop history buffer,determining an average drop rate based on at least the detection timesincluded in the history buffer, and determining a drip stability basedon a comparison of a plurality of temporal distances between thedetection times included in the drop history buffer. In someembodiments, the device may include a battery. In some embodiments,power provided to at least one of the detector and the source is pulsed.The provided power may include a bias current. In at least one of thevarious embodiments, bias current provided to the detector and sourcesis pulsed at a predetermined frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is generally directed to a Brief Description ofthe Drawings. Preferred and alternative examples of the presentdisclosure are described in detail below with reference to the followingdrawings:

FIG. 1A shows a flow rate monitoring device adjacent to a gravity fedinfusion set that includes a drip chamber according to embodiments ofthe present disclosure.

FIG. 1B shows a flow rate monitoring device affixed to a drip chamberincluded in a gravity fed infusion set according to embodiments of thepresent disclosure.

FIG. 2 shows a top-down view of a flow rate monitoring device affixed toa drip chamber according to embodiments of the present disclosure.

FIG. 3 shows an exploded view of a flow rate monitoring device with adrip chamber positioned within an optical path between a source anddetector according to embodiments of the present disclosure.

FIG. 4 shows a block level diagram of electronic components included invarious embodiments of a flow rate monitoring device described in thepresent disclosure.

FIGS. 5A and 5B show time series of generated waveforms based on EMRdetection signals as described in the present disclosure.

FIG. 6 shows embodiments of methods for operating a monitoring device.

FIG. 7 shows an embodiment of a clip-style monitoring device bodyaccording to embodiments in the present disclosure.

FIGS. 8A, 8B, and 8C show various views of a monitoring device accordingto embodiments of the present disclosure.

DETAILED DESCRIPTION

As described in greater detail herein, the present disclosure providesdevices, methods, and systems for providing real time monitoring of afluid flow rate and an accumulated total volume through a drip chamber.Certain aspects of these devices, methods, and systems can be betterunderstood by reference to the following non-limiting definitions.

DEFINITIONS

Terms defined herein have meanings as commonly understood by a person ofordinary skill in the areas relevant to the present disclosure. Termssuch as “a,” “an,” and “the” are not intended to refer to only asingular entity, but include the general class of which a specificexample may be used for illustration. The terminology herein is used todescribe specific embodiments of the disclosure, but its usage does notdelimit the disclosure, except as outlined in the claims.

As used herein, the term “electromagnetic radiation” (EMR) is notintended to be limiting. In contrast, as used throughout the presentdisclosure, EMR may refer to any form of energy relating to thepropagation of electromagnetic waves and/or photons. The term EMR is notlimited to a specified range of wavelengths or frequencies within theelectromagnetic spectrum. Rather, EMR, as used herein may include radiowaves, microwaves, infrared (IR) radiation, visible light, ultraviolet(UV) radiation, X-rays, gamma rays, or any other such wavelengths orfrequencies of EMR.

As used herein, the terms “EMR source” and “source” are not intended tobe limiting. In contrast, as used throughout the present disclosure,both “EMR source” and “source” may refer to any device enabled to emitEMR. Non-limiting examples of sources include light emitting diodes(LEDs), lasers, light bulbs, and the like.

As used herein, the terms “EMR detector” and “detector” are not intendedto be limiting. In contrast, as used throughout the present disclosure,both “EMR detector” and “detector” may refer to any device enabled togenerate a signal when in the presence of EMR. In some embodiments, thenature of the signal may be electrical, optical, mechanical, or acombination thereof. A generated electrical signal may be analog ordigital in nature. Some detectors may be referred to as photodetectorsor photosensors. Non-limiting examples of detectors include photodiodes,reverse-biased LEDS, active-pixel sensors (APS), avalanche-photodiode(APD), charge-coupled devices (CCD), photoresistors, photomultipliertubes, photovoltaic cells, and the like.

As used herein, the term “processor device” is not intended to belimiting. Rather, as used throughout the present disclosure, processordevice may refer to one or more devices enabled to execute instructionsthat perform actions. In some embodiments, a processor device mayreceive input and provide corresponding output in response to thereceived input. In some embodiments, processor device may include aprogrammable microcontroller. In some embodiments, a processor devicemay include a microprocessor. A processor device may include a fieldprogrammable gate array (FPGA). In other embodiments, a processor devicemay include an application specific integrated circuit (ASIC). In someembodiments, a processor device may include a computer and/or a mobiledevice. In some embodiments, a processor device may include a processingcore, memory, input/output peripherals, logic gates, Analog-to-DigitalConverters (ADCs) and such. In some embodiments, a processor device mayinclude a plurality of processor devices in communication with oneanother across a network or a bus.

Briefly stated, various embodiments of the devices, methods, and systemsincluded herein are directed towards, but not limited to monitoring theflow rate and total volumetric amount of a fluid, or accumulated fluiddose, delivered to a target through an infusion set. The target may be amedical patient and the fluids may be delivered intravenously.

A handheld monitoring device may be affixed to a drip chamber includedin the infusion set. By employing an embedded EMR source and an embeddedEMR detector, individual drops falling within the drip chamber may bedetected and counted in real time. Furthermore, the time between eachsuccessive drop may be determined By monitoring the rate of dropsfalling in the drip chamber and applying an appropriate drip factor, afluid flow rate may be determined. Also, a total volumetric amount, oraccumulated dose, of fluid delivered to the target may be determined.

The determined flow rate and total accumulated fluid dose may beprovided in real time, to a user, through a user interface. The userinterface may include a display unit, input buttons or an alpha-numerickeypad, and an audible speaker. In some embodiments, the user input andoutput functions may be enabled through a touch-sensitive displaydevice.

The user may provide various input information, such as the drip factor,the target fluid flow rate, the target total dose, target flowstability, and the like, through the user interface. The user may alsoprovide corresponding tolerances and/or ranges associated with thesetarget parameters through the user interface.

If the flow becomes unstable, the monitored flow rate falls outside of atolerance range, a total volumetric dose has been achieved or surpassed,or if the flow ceases, the device may provide various alerts to a user.These alerts may include audio alerts provided by the speaker. Thealerts may also include visual alerts provided by the display device. Insome embodiments, at least some of the alerts may be provided in realtime to remote devices, including but not limited to servers/clients,mobile devices, desktop computers, and the like.

Furthermore, the handheld device may be attached or affixed to the dripchamber with a spring-loaded clip. In other embodiments, a trench or achannel included in the monitoring device may enable “snapping” thedevice onto the clip chamber. The device may be battery operated orpower may be supplied through an external source, such as a wall socket.Some embodiments may include a backup battery. In at least one of thevarious embodiments, power may be supplied to a monitoring device byemploying a solar-powered battery.

In some embodiments, the device may be networked to remote devices, suchas a remote computer, a smart phone, or a tablet. Through network means,the device may provide real time information to such remote devices. Aremote user may operate the user interface remotely. In someembodiments, the device may be operated and monitored through anapplication, such as an app running on a mobile device.

Furthermore, the device may be enabled to generate log files includingthe monitored flow rates, corresponding stabilities, and total deliveredfluid dosages. The log files may also include other operationalparameters, such as user provided inputs. These log files may beincluded in a patient's medical history files. In some embodiments, aremote networked computer may monitor the device and generate the logfiles. The log files may be provided to and archived by other systems,such as cloud-based storage systems.

Although many embodiments included herein are discussed in the contextof delivering fluids through an infusion set, it should be understoodthat the present invention is not so limited. The present invention maybe used in any context where fluids are being transported in the form ofindividual drops, for at least a portion of the total distance that thefluid is being transported. For instance, the present invention may beemployed in any context where fluids drops are detectable. Examplesinclude, but are not limited to fluid flowing through a drip chamber, anozzle, a valve, an aperture, or the like. Such contexts include, butare not limited to industrial uses, governmental/academic/industrialresearch, and the like.

FIG. 1A shows an embodiment of flow rate monitoring device 100 adjacentto infusion set 190. In some embodiments, infusion set 190 may be agravity fed infusion set, although the present invention is not soconstrained. For instance, other means of inducing drop flow through apathway, such as a pump, may be employed in various embodiments. In atleast one of the various embodiments, flow rate monitoring device 100may be a handheld device. Flow rate monitoring device 100 includesdisplay unit 102. Display unit 102 may provide a user with real timedata based on at least the monitored flow of fluid through infusion set190. Although not shown in FIG. 1A, some embodiments may also include anaudio interface, such as an audio speaker. An audio interface mayprovide the user with audio information, such as an audible alert whenthe monitored flow rate is outside of a specified range.

Monitoring device 100 includes user input interface 106. User inputinterface 106 may enable a user to provide inputs to the device such as,but not limited to, target flow rate, tolerance ranges, drip factors,lag times, lockout times, stability ranges, alarming functionality,display units, and the like. In some embodiments, input interface 106may include buttons, alpha-numeric keypads, and the like. In someembodiments, input interface 106 may be integrated with display unit 102by employing a touch sensitive display unit. Although not shown, in atleast some embodiments, monitoring device 100 may include an audio inputdevice, such as a microphone. Some embodiments may include voicerecognition software so that a user may provide inputs through the audioinput device. Monitoring device 100 includes coupler 104. Coupler 104enables affixing or attaching monitoring device 100 to infusion set 190.

Infusion set 190 includes fluid source 191. Fluid source 191 may be anIV bag. Infusion set 190 may include a suspension means 193, such as aloop or hook attached to fluid source 191. Infusion set 190 may besuspended in a gravity field by employing suspension means 193. Thesuspension of infusion set 190 allows gravity to induce fluid flowthrough infusion set 190. When affixed to fusion set 190, monitoringdevice 100 may be suspended along with infusion set 190. In at least oneof the various embodiments, coupler 104 may include a clip.

Infusion set 190 may include drip chamber 192. Due to gravity, fluidfrom fluid source 191 flows through drip chamber 192. Also, infusion set190 may be enabled so that as long as the flow rate through infusion set190 is below a critical threshold, the fluid flowing through dripchamber 192 is in the form of individual fluid drops. If the fluid flowrate is above the critical threshold, fluid flowing through drip chambermay become a continuous stream of fluid.

Some elements of infusion set 190 may be characterized by a drip factor.Drip factors depend upon physical characteristics of specific elementsof infusion set 190, such as drip chamber 192 and tubing components suchas fluid output 198, and combinations thereof. Drip factors correspondto the volume of fluid in each individual fluid drop that flows througha drip chamber of the specific infusion set. Drip factors may beexpressed in units of gtt/mL, or drops per milliliter (mL) of fluid. Forinstance, for 1 mL of fluid to flow through an infusion set with a dripfactor of 10 gtt/mL, 10 individual drops of fluid must flow through thedrip chamber. Exemplary, but non-limiting, drip factor valuescorresponding to the combination of the various elements of infusion set190 may include 10, 15, 20, and 60 gtt/mL. Throughout the presentdisclosure, references to an infusion set's drip factor may refer to thevalue of the drip factor corresponding to the combination of the variousinfusion set elements that a drip factor depends upon.

In some embodiments, drip factors may be expressed in alternative units,such as mL/gtt. In other embodiments, the drip factor may be expressedin drops per unit mass or weight if the density of fluid is known. Dripfactors may also be expressed in mass or weight per drop. It isunderstood that the present disclosure is not limited to such exampledrip factors, and may accommodate any other appropriate values, units,or alternative ways to express drip factors.

A flow rate of drops through drip chamber 192 may be converted to afluid flow rate and vice versa based on the drip factor corresponding toinfusion set 190. Additionally, a total number of drops, or accumulatedflow of fluid may be determined by integrating or determining a sum ofthe flow rate of drops or fluid flow rate respectively, over successivepoints in time.

Infusion set 190 includes user handle 194 and roller clamp 196. Byvarying the position of roller clamp 196 along an edge of user handle194, the combination of user handle 194 and roller clamp 196 enables auser to control the flow rate of individual fluid drops through dripchamber 192, and thus the flow rate of fluid through infusion set 190.Infusion set 190 includes fluid output 198. Fluid output 198 deliversfluid, originating at fluid source 191, to the intended target, and atthe flow rate corresponding to the position of roller clamp 196.

FIG. 1B shows flow rate monitoring device 100 attached to infusion set190 by employing coupler 104. In some embodiments, monitoring device 100may be attached to infusion set 190 by attaching or affixing monitoringdevice 100 to the drip chamber, which is hidden from view by monitoringdevice 100.

In some embodiments, including at least embodiments discussed in view ofFIGS. 8A, 8B, and 8C, at least a portion of the drip chamber may bevisible to a user when the monitoring device is affixed to the infusionset. Providing the user visibility to at least a portion of the dripchamber during operation of the monitoring device may enable the user tovisually inspect fluid drops within the channel. In at least one of thevarious embodiments, the monitoring device is affixed to the chamber byemploying a trench or channel that provides the user visibility to atleast a portion of the drip chamber. In some embodiments, when infusionset 190 is suspended or otherwise repositioned, monitoring device 100remains affixed to the drip chamber.

FIG. 2 shows a top-down view of an embodiment of flow rate monitoringdevice 200 affixed to drip chamber 292. Monitoring device 200 includesdevice body 250. Monitoring device 200 includes cavity 258. In someembodiments, cavity 258 may be a cavity, hole, trench, depression, oraperture within device body 250. In some embodiments, cavity 258 mayinclude at least one inner surface.

When monitoring device 200 is attached to drip chamber 292, drip chamber292 may be positioned within cavity 258. In at least one embodiment,cavity 258 may be configured and arranged to receive at least a portionof drip chamber 292. The at least one inner surface of cavity 258 mayprovide a gripping or otherwise frictional force that grips an outersurface of drip chamber 292. This gripping force may enable stabilizingthe monitoring device 200 about drip chamber 292.

In some embodiments, the fit between the outer surface of drip chamber292 and inner surface of cavity 258 may be snug and lack gaps. As shownin FIG. 2, in some embodiments, gaps between at least portions on theouter surface of drip chamber 292 and inner surface of cavity 258 mayexist when monitoring device 200 is affixed to drip chamber 292. In someembodiments, monitoring device 200 may accommodate drip chambers ofvarying shapes and dimensions by outfitting the inner surface of cavity258 with at least one of a compressible gripping material, cammingdevice, or a textured portion.

Monitoring device 200 includes source 210 and detector 212. Source 210may be enabled to emit EMR. In some embodiments, the operation of source210 may allow for controlling at least the timing and/or the intensityof the emission of EMR from source 210. Detector 212 detects the EMRemitted by source 210 and generates a corresponding signal. In someembodiments, source 210 may be an LED. In some embodiments, source 210may be enabled to emit EMR within a specified range of wavelengths orfrequencies. In some embodiments, source 210 may be an infrared emittingdiode (IRED).

In various embodiments, detector 212 may be a photodiode. Detector 212may be enabled to detect the specified range of wavelengths orfrequencies of EMR emitted by source 210. In some embodiments, detector212 may be more sensitive to the specified range of wavelengths emittedby source 210 than to other wavelengths. For instance, if source 210emits IR EMR, then detector 212 may be enabled to generate a moresensitive signal in the presence of IR EMR, than in the presences ofother wavelengths of EMR, such as visible light.

In some embodiments, source 210 and detector 212 may be in oppositionalong the inner surface of cavity 258. When aligned in opposition,source 210 and detector 212 form an optical path across cavity 258. EMRemitted by source 210 and travelling along the optical path may bedetected by detector 212. Such an optical path is shown across cavity258 by the dotted line.

In some embodiments, drip chamber 292 may be at least partiallytransparent, semi-transparent, or translucent to the wavelengths of EMRemitted by source 210. When monitoring device 200 is affixed to dripchamber 292, an optical path across drip chamber 292 is formed. If nofluid is within the optical path, then at least a portion of the EMRemitted by source 210 is detected by detector 212. The portion of EMRemitted by source 210 and detected by detector 212 may generate abaseline detector signal, as will be described in conjunction with FIGS.5A and 5B, below.

At least a portion of device body 250 may be configured as a clip, suchas a tension- or spring-loaded clip. A spring loaded clip may be openedby overcoming the tension with an external force, such as a user openingthe clip. In the absence of such an external force, the clip may be in aclosed state. When drip chamber 292 is positioned within cavity 258, thetension or spring force of the clip may provide a stabilizing force toaffix monitoring device 200 to drip chamber 292.

To provide leverage to a user in assistance in opening the clip, one ormore clip handles 252 may be included with device body 250. In someembodiments, spring 256 may provide at least a portion of the force thatcloses the clip and affixes device 200 to drip chamber 292. Duringopening and closing of the clip, at least a portion of the clip maypivot about hinge 254.

FIG. 3 provides an exploded view of flow rate monitoring device 300 withdrip chamber 392 positioned within the optical path 320 between source310 and the corresponding detector (hidden from view). The dotted linedemarcates optical path 320.

Drip chamber 392 is configured and arranged such that fluid enteringdrip chamber 392 from the top, drips as individual drops, and forms apool of fluid at the bottom of drip chamber 392. Fluid in the pool thenflows out of drip chamber 392 and into fluid output 398. Fluid flowingthrough fluid output 398 is ultimately delivered to the target.

During steady state operation of an infusion set, the volume of the poolof fluid at the bottom of drip chamber 392 remains approximatelyconstant. In such steady state operation, the rate of fluid delivered tothe target through fluid output 398 (in units of mL per unit time) maybe determined based on a ratio of the number of fluid drops falling indrip chamber 392 per unit time to an appropriate drip factor in units ofgtt/mL. An accumulated volume of fluid delivered to the target maysimilarly be determined based on a ratio of a total number of fluiddrops that have fallen in drip chamber 392 to the drip factor.

Three individual fluid drops are shown at various points falling fromthe top of drip chamber 392 towards the pool of fluid at the bottom ofdrip chamber 392. The amount of time an individual drop takes from firstbeginning to drop from the top of drip chamber 392 to the time itreaches the pool at the bottom of drip chamber 392 may be referred to asdrop time-of-flight.

Monitoring device 300 is configured and arranged, such that when affixedto drip chamber 392, each fluid drop passing through drip chamber 392will pass through optical path 320 during a portion of the drop'stime-of-flight. Fluid drop 393 is shown within optical path 320. Thetime period during which a drop is within optical path 320 may bereferred to as the drop's line-of-sight period. The length of a drop'sline-of-sight period may be referred to as the drop's line-of-sighttime.

In some embodiments, the fluid drops passing through drip chamber 393are not completely transparent to at least a portion of the EMRwavelengths emitted by source 310. At the very least, the combination ofdrip chamber's 392 walls and fluid drop 393 is less transparent to theemitted EMR than drip chamber's 392 walls without fluid drop 393 inoptical path 320. Thus, during the drop's line-of-sight period, fluiddrop 393 will at least partially inhibit EMR emitted from source 310from travelling across optical path 320. For instance, fluid drop 393may partially obscure or refract EMR within optical path 320 during itscorresponding line-of-sight period.

Because EMR emitted from source 310 will be at least partially inhibitedduring fluid drop's 393 line-of-sight period, a response of the detectorwill vary, producing a signal different than that of the signal producedwhen no fluid is within optical path 320. The signal produced by thedetector when fluid is not within optical path 320 may be referred to asthe detector's baseline signal.

As provided in more detail below in regards to FIGS. 5A and 5B,monitoring device 300 may be enabled to use the varying signal generatedby the detector to detect in real time, each individual fluid drop as itpasses through drip chamber 392. Based on at least the detection of eachindividual fluid drop, monitoring device 300 may be enabled to determinea total number of fluid drops that have passed through drip chamber 392.By applying the appropriate drip factor to convert number of drips intovolume of fluid, monitoring device 300 may determine a total volume offluid delivered to the target through fluid output 398.

In various embodiments, monitoring device 300 may be enabled todetermine the amount of time between each successive detected fluid dropin drip chamber 392. By detecting a plurality of individual drops overtime, monitoring device 300 may determine a fluid drop rate, such as thenumber of drops per unit time. By applying the appropriate drip factor,monitoring device 300 may determine a volumetric fluid flow ratedelivered to the target through fluid output 398. As provided in moredetail with regards to FIG. 6, monitoring device 300 may determine arolling average and an associated stability of the number of drops perunit time and the volume of fluid per unit time.

In at least one of the various embodiments, monitoring device 300 maydetermine if a determined drop or volumetric flow rate falls outside ofa specified range, such as +−10% of a nominal or target value. Suchinstabilities may occur when a patient changes positions, the IV bagchanges positions, tubing pressure changes, the position of a rollerclamp is accidently altered, the infusion set becomes clogged, the IVbag is depleted and such.

Monitoring device 300 may provide a user with these determinations andadditional information by employing display unit 302. In someembodiments, monitoring device 300 may provide alerts to a user. Suchalerts may be triggered when determinations, such as instabilities in adrop or fluid flow rate, do not match target values within a specifiedrange. Alerts may be provided when an accumulated total target volume offluid has been delivered or the total target volume has been exceeded.Alerts may be provided through display device 302 and/or through anaudio interface, such as a speaker. In at least some embodiments, alertsprovided to the user may include visual alerts, such as alerts providedby an LED that emits at least optical frequencies of EMR or other suchsources of light, including light bulbs or optical lasers. Alerts may beprovided by rapidly pulsing audio or visual signals, such as a strobelight or a siren. Users may provide monitoring device 300 with targetvalues for such metrics that are monitored, through user inputinterfaces, such as user input interface 106 of FIGS. 1A and 1B.

Some embodiments may be networked to remote devices and supply users ofthe remote devices with such information and alerts. Some embodiments ofmonitoring device 300 may include non-volatile memory devices thatenable the creation of log files including one or more metricsdetermined and monitored by monitoring device 300. Log files may includevalues of user inputs, such as target volume or target flow rates. Logfiles may include other data, such as the amount of time that fluid wasflowing through a drip chamber, time stamps for each individuallydetected drop, drop waveforms, and other diagnostics, acquired data, andoperating conditions.

By employing a networked monitoring device, data may be provided toremote devices. Such provided data may be used by remote devices togenerate log files. These log files may be archived for future accessand may become part of a patient's medical history. These log files maybe used as input data for clinical tests or other research or industrialpurposes. For example, log files may be employed in the production of orresearch regarding energy sources, such as biofuels.

FIG. 4 shows a block level diagram of components included in variousembodiments of flow rate monitoring devices described throughout thepresent disclosure. One such monitoring device may be monitoring device100 of FIG. 1. In some embodiments, a monitoring device may include aprocessor device. In at least one of the various embodiments, aprocessor device may include a programmable microcontroller, such asmicrocontroller 416.

A monitoring device includes a source. In some embodiments, a source mayinclude LED 410. LED 410 may be an infrared (IR) LED, such as an IRED.At least one terminal of LED 410 may be tied to ground. A monitoringdevice may include a detector. In some embodiments, detector may includephotodiode 412. Photodiode 412 may have a greater sensitivity to IRwavelengths than to wavelengths within the visible light spectrum. Insome embodiments, sense resistor 414 may be used in conjunction withphotodiode 414. Sense resistor may be between photodiode 412 and ground.

In some embodiments, microcontroller 416 may control the operation of atleast one of LED 410 and photodiode 412. Such controls may includecontrolling a pulsing of biasing currents used in the operation of LED410 and photodiode 412. Furthermore, microcontroller 416 may monitor oneor more signals from photodiode 412, including at least an EMR detectionsignal generated by photodiode 412 and in response to detecting EMRemitted from LED 410.

The EMR detection signal may be a digital signal. However, in at leastsome embodiments, the EMR signal may be an analog signal. If the EMRdetection signal is an analog signal, the EMR detection signal may bedigitized before being provided to microcontroller 416. In otherembodiments, the EMR detection signal may be provided to microcontroller416 as an analog signal. In some embodiments, no pre-amplification maybe required of the EMR detection signal prior to being provided tomicrocontroller 416. In these embodiments, the ability to providemicrocontroller 416 the EMR detection analog signal withoutpre-amplification reduces the total number of components required formanufacturing a monitoring device. This reduction in component count mayresult in reducing cost and/or complexity of the monitoring device.

Monitoring devices may operate in a “continuous mode” or a “samplemode.” In some embodiments, at least one of LED 410 and photodiode 412may be operated at a 100% duty cycle during the operation of themonitoring device. In these “continuous mode” embodiments, fluid dropdetection measurements may be made continuously.

In order to reduce operating power requirements, at least one of LED 410and photodiode 412 may be operated at less than a 100% duty cycle. Insuch “sample mode” embodiments, fluid drop detection measurements may bemade periodically or in samples rather than continuously. Thus, samplemeasurements may be made at a predetermined frequency.

The amount of time an individual fluid drop, such as fluid drop 393 ofFIG. 3, is within the monitoring device's optical path, such as opticalpath 320, may be referred to as the drop's line-of-sight time. In someembodiments, time between consecutive samples, or sample period, may beless than a drop's line-of-sight time. In at least one of the variousembodiments, the sample period may be significantly less than a drop'sline-of-sight time. As will be shown in conjunction with FIGS. 5A and5B, employing a sample period significantly less than a drop'sline-of-sight time allows for the generation of a drop's waveform ortime profile.

In some embodiments, LED 410 and photodiode 412 are operated for only afraction of a sample period for each sample measurement. For instance,for a sample frequency of 1 kHz, a sample measurement is obtained every1 millisecond (ms). In some embodiments, 1 ms is significantly less thanany individual drop's line-of-sight time. To sample the transparency ofoptical path 320 during a single sample measurement, bias current issupplied to LED 410 and photodiode 412 for a length of time referred toas an operation time. The operation time may be less than the sampleperiod. For instance, for a sample period of 1 ms, the bias current maybe supplied to LED 410 and photodiode 412 for only about 10microseconds. An operation time of 10 microseconds results in anoperational duty cycle of (10 microsecond)/(1 ms), or 1%.

“Sample mode” embodiments may enable monitoring devices withsignificantly lower power consumption requirements because biasingcurrents are only being supplied to the source and detectors for a smallfraction of the time. Operation times may be based on one or morecharacteristics such as source and detector rise and fall times,operating speed of a processor device, optical transparency of the fluidand/or drip chamber walls, length of drip chamber, response times ofvarious components and/or circuits included in the monitoring device,and the like.

It is understood that the numerical values for sample frequency sampleperiod, operation time, as well as all other numerical values usedherein are for illustrative purposes only, and the disclosure is not soconstrained by the values provided herein. Rather, these values arechosen for their illustrative purposes. In some embodiments, sampleperiods and the like may be varied to account for detector responsetimes, length of drip chambers, characteristics of the fluid,characteristics of sources/detectors such as rise/fall times, and thelike.

In some embodiments, microcontroller 416 may control the pulsing ofbiasing currents for LED 410 and photodiode 412. Some embodiments may beenabled to operate in both “continuous” and “sample” modes. In suchembodiments, a user may be enabled to select which mode to operate in,as well provide programmable operational parameters such as samplingfrequency, duty cycles, and the like.

Various embodiments may include a power supply. The power supply maysupply power to various components, such as microcontroller 416, as wellas other components. In some embodiments, the power supply may be aninternal power supply, such as battery 418. Battery 418 may bereplaceable. Furthermore, battery 418 may be rechargeable. Someembodiments may include more than one battery to provide redundancy.Some embodiments may account for an external power supply, such as wallmounted sockets. Some embodiments may be enabled to employ both anexternal and an internal power supply, depending on the needs of a userand the context of operation. For instance, some monitoring devices maybe powered by a wall socket, and also include a backup battery in theevent of a loss of power to the wall socket. In at least one of thevarious embodiments, the power source may include a photovoltaic cell,such as a solar cell.

Monitoring devices may include display unit 402. Display unit 402 may beemployed to provide information to a user. Such information may include,but is not limited to, determined fluid flow rates, fluid drop rates,percentage or absolute amount of battery power remaining, the dripfactor currently be used by the monitoring device, total accumulateddrops, total accumulated fluid flow, and the like. Microcontroller 416may control at least a portion of display unit 402.

Monitoring devices may include a user input interface. A user inputinterface may include button inputs 406. Button inputs 406 may be usedby a user to provide the device with various user inputs, such as dripfactor, target fluid drop rate, target fluid flow rate, target totalaccumulated fluid flow, etc. In some embodiments, a user may togglebetween “continuous mode” and “sample mode” of operation by employingbutton inputs 406. In some embodiments, a user may provide a monitoringdevice with a target duty cycle or other such input information byemploying button inputs 406.

Monitoring devices may include an audio interface, such as alerttransducer 408. Alert transducer 408 may be a speaker used to provideaudio alerts and other audio information to a user. Microcontroller 416may communicate with display unit 402, button inputs 406, and alerttransducer 408 and supply inputs and outputs to these and other devices.

Although not shown, it is understood that various other components, suchas charge pumps, may be used in embodiments. Digital memory devices maybe included in various embodiments. Memory devices may be volatile ornon-volatile memory devices. Memory devices may include, but are notlimited to RAM, ROM, EEPROM, FLASH, SRAM, DRAM, optical disks, magnetichard drive, solid state drives, or any other such non-transitory storagemedia. Memory devices may be used to store various information,including but not limited to programmable user inputs, monitoredmetrics, log files, or operational parameters.

Although not shown, it is understood that various embodiments ofmonitoring devices may include a network transceiver device. Suchnetwork transceivers may be enabled to communicate with other devicesover a wired network or a wireless network. Such transceivers may beenabled with WiFi, Bluetooth, cellular, or other data transmission andnetworking capabilities. In such embodiments, monitoring devices may beenabled to communicate with other devices. These other devices mayinclude remote computer devices, such as servers, clients, desktops, andmobile devices.

Users may supply inputs to the monitoring device by the remote use ofthese networked computer devices. Furthermore, users may be enabled tomonitor, in real time, information supplied by the monitoring devices,through the use of remote computing devices. Health care providers maybe enabled to remotely monitor patients from afar. For instance, doctorsor nurses, in one area of a hospital may be able to remotely monitor theIV drips for patients located in other areas of the hospital. Mobiledevices, such as tablets or smartphones may be employed for such remote,real-time monitoring.

Also, the networking capabilities may enable data logs for patients tobe generated and archived. These data logs, or log files, may becomepart of a patient's medical history. Furthermore, these log files may beemployed as evidence regarding a standard of care provided to thepatient.

FIGS. 5A and 5B show time series plots of generated waveforms based onEMR detection signals. In some embodiments, a waveform may include atemporally ordered plurality of points, each corresponding to a detectorsignal. Each point in a waveform may include a time coordinate and adetector signal coordinate. Because the points are temporally ordered,characterization of points as prior, current, and subsequent point arewell defined. Also, a distance between points, such as a time distancebetween points is well defined.

In FIGS. 5A and 5B, the unprocessed EMR detection signals may be analogsignals from a detector, such as photodiode 412 of FIG. 4. The analogsignals may be digitized prior to the generation of waveforms. In someembodiments, the digitization may occur within a processor device, suchas microcontroller 416 of FIG. 4. A digitization process may employ anAnalog-to-Digital Converter (ADC), internal to microcontroller 416. FIG.5A shows a pre-processed drop waveform 522. The x-axis represents thetime of a sampled detector reading in milliseconds. The y-axisrepresents an ADC value based on the signal generated by the detector ateach sampled time.

In FIG. 5A, the start of a fluid drop, such as fluid drop 393 of FIG. 3,entering an optical path, such as optical path 320 of FIG. 3, is markedat approximately 20 ms. Furthermore, the time that the fluid drop exitsthe optical path is marked at approximately 36 ms. Thus, the dropline-of-sight time is approximately 16 ms.

Note the variance in value of waveform 522 during the line-of-sightperiod. A two peak structure may be characteristic of some fluid drops.Note the two peak structure in waveform 522, where the first peak ismarked at approximately 27 ms, and the second peak occurs atapproximately 29 ms. This variance in the digitized signal value is dueto the fluid drop inhibiting EMR emitted by a source, such as LED 410,from flowing across the optical path.

Also note the baseline signal, with an ADC count of approximately 183,corresponding to the uninhibited flow of the EMR across the opticalpath. Noise fluctuations are also shown on drop waveform 522. In someembodiments, these noise fluctuations may be filtered using hardwareand/or software based filters.

In some embodiments, drops may be detected by employing a processordevice, such as microcontroller 416 of FIG. 4, to analyze drop waveformsin real time, such as exemplary drop waveform 522. Some embodiments mayutilize a method of analyzing drop waveforms that includes a comparisonof the waveform at each sample to an absolute threshold, such as acalibration threshold or an averaged or filtered value of the baselinesignal, shown in waveform 522.

Other embodiments may compare at least a portion of the points inwaveform 522 to other points in waveform 522. In such embodiments, thedetector signal at various sample times may be employed to generatedifference waveforms. Such difference waveforms may result in differencesignals that are characteristic to the detection of fluid drops. Forinstance, the detector signal (or ADC count) at each sample may becompared to the detector signal (or ADC count) from a prior sample. Anamount of time between the time corresponding to the current sample andthe time corresponding to the prior sample may be referred to as lagtime.

A lag time difference waveform may be determined by first generating apre-processed waveform, such as waveform 522. Subsequent to generatingpre-processed waveform 522, a difference between each point included inat least a portion of the points on pre-processed waveform 522 and aprior point on pre-processed waveform 522 may be determined, where thetwo points used to generate the difference are separated by a timedistance equal to the lag time.

FIG. 5B shows lag time difference waveform 524, which is a simpledifference waveform. Simple difference waveform 524 was generated usinga lag time equivalent to the sample period. In other words, eachinstance of the detector signal is compared to the immediate priorsample. For simple difference waveform 524, the sample period is equalto the lag time (1 ms) and the drop line-of-sight time is approximately16 ms. Detecting a fluid drop from a simple difference waveform mayprove difficult because unless the absolute values of the timederivative of the pre-processed waveform 522 are large enough, theliquid drop signal resulting from a simple difference waveform may besmall, as shown in simple difference waveform 524.

Other choices of lag time may be more advantageous. In order to producea better signal-to-noise ratio, a larger lag time may be employed. Suchlarger lag times may produce difference signals more characteristic of afluid drop, resulting in a suppression of false positive and falsenegative fluid drop detections. Some embodiments may employ a lag timeapproximately equal to half a drop's line-of-sight time. Such a valuemay result in a larger time difference signal. Such a value may enhancethe likelihood of successfully detecting a fluid drop. This is becausethe peak structure of the unprocessed waveform is compared to thebaseline signal of the waveform, resulting in a larger time lagdifference signal that is indicative of a fluid drop.

For instance, lag time difference waveform 526 was generated fromwaveform 522 by using a lag time of 8 ms. Note the amplitude of thesignals in lag time difference waveform 526 with simple differencewaveform 524. The greater signal amplitude of time difference waveform526 may result in better drop detection. Also note both the positive andnegative structure of waveform 526. The negative and positive peaks oflag time difference waveform 526 result from the comparison of the peakstructure of pre-processed waveform 522 in comparison to the baselinedetector signal prior to and subsequent to the drop's line-of-sightperiod, respectively. This adjacent negative and positive peak structureassociated with an appropriate choice of lag time may be acharacteristic signal of a fluid drop detection. Thus, such appropriatechoices for a lag time may result in a better signal to noise ratioand/or an increase in drop detection accuracy; including at leastsuppressing both false positive and false negative detections.

Waveform 526 may not be sensitive to long-term changes of signal value,but it largely retains the high signal to noise ratio of waveform 522.The waveform 522 may exhibit a large signal difference between thesignal baseline and the negative peak. However, the specific ADC countvalues of the baseline and the peak will vary based on a variety offactors including but not limited, to source brightness, shape, andmaterial of the drip chamber, ambient light, drip position, andcondensation on the drip chamber. No single threshold value fordetecting a drip will be robust to changes in these environmentalfactors.

The waveforms 524 and 526 are not sensitive to long-term changes insignal value, so the above factors do not affect the signal. However,the signal to noise ratio of waveform 524 is low, which may lead toproblems with false positives and negatives. Waveform 526 is notsensitive to long-term changes of signal value, but it largely retainsthe high signal to noise ratio of waveform 522.

In some embodiments, the lag time is chosen to be longer than a falland/or rise time of the detector. In at least one of the variousembodiments, an employed lag time is longer than several sample periods,but shorter than the drop line-of-sight time. For instance, a lag timeof 8 ms is shorter than a line-of-sight time of 16 ms (and isapproximately half the drop's line-of-sight time), but longer than asample period of 1 ms, as shown in waveforms 526. A lag time longer thanthe drop line-of-sight time may fail to detect fluid drops. In someembodiments, the lag time may be varied depending on the particular useof a monitoring device. In some embodiments, a user may be enabled toprovide a lag time to use during a particular operation.

In some embodiments, a lag time difference waveform, such as lag timedifference waveform 526, generated based on an appropriate lag timevalue, may be employed in detecting each individual drop. By employingat least a processor device, such as microcontroller 416 of FIG. 4, dropdetection may be performed in real time, as the drop is falling in thedrip chamber. Lag time difference waveforms may be analyzed to detectthe fluid drops. In various embodiments, drop detection may be based onthe shape of a plurality of lag time difference waveforms generated byemploying an appropriate lag time value.

Some embodiments may employ a lockout method to enable a vetoing offalse positive drop detections. It is possible for a detector signal topresent a drop profile at more than one instant in time. For instance,if the time difference between the detection of a first drop and asecond drop is below a lockout threshold, then at least one of thedetections is determined as a spurious detection. A spurious detectionevent may trigger the vetoing of at least one of the two dropdetections.

In some embodiments, the waveforms corresponding to vetoed, or lockoutdetections, may be included in a log file for future analysis. In someembodiments, the detection of a plurality of lockout events within aminimum amount of time may signal that the drop rate is unstable, orthat the drops or flowing too quickly within the drip chamber to enableindividual drop detections. Some embodiments may provide a user with anaudio or visual alert in the event of one or more lockout events.

The lockout threshold or period may be chosen to be longer than a dropline-of-sight time, but shorter than an average drop rate. In someinstances, a user may supply the lockout threshold. In some embodiments,the lockout threshold may be varied to account for a current averagedrop rate.

FIG. 6 shows embodiments of method 630 for operating a monitoringdevice. Methods, such as method 630, may be performed by a processordevice, such as microcontroller 416 of FIG. 4. A processor device mayexecute instructions that perform actions. At block 631, a drop isdetected within a drip chamber, such as drip chamber 392 of FIG. 3, attime t. The drop may be detected using various methods, such as, but notlimited to, the various embodiments discussed in reference to FIGS. 5Aand 5B. If the drop is not vetoed as a lockout event, then method 630may proceed to block 632.

At block 632, the detected drop is added to a drop history buffer. Insome embodiments, the buffer may be stored in at least a memory deviceincluded in the monitoring device. The memory device may be a volatileor non-volatile memory device. Adding the detected drop to the drophistory buffer may include adding a detection time to the buffer. Insome embodiments, a drop line-of-sight time corresponding to the addeddrop may be added to the buffer. In at least one of the variousembodiments, at least a portion of the detector signal associated withthe added drop may be added to the buffer. At least one waveform, suchas any of 522, 524, or 526 of FIGS. 5A and 5B may be added to thebuffer. A total drop count associated with the detected drop may beadded to the buffer. In some embodiments, the buffer includes aplurality of previously detected drops.

If a monitoring device is operated in a manual transition mode, method630 branches to manual transition method 633 and proceeds to block 635.If the monitoring device is operated in automatic transition mode,method 630 branches to automatic transition method 641 and proceeds toblock 642. In at least one of the various embodiments, a user may beenabled to select manual transition mode or automatic transition mode byemploying a user input interface, such as user input interface 106 ofFIGS. 1A and 1B.

At block 635 and block 642, the drop history buffer is trimmed to aspecified time span. The specified time span may depend on an availablesize of the buffer, such as the amount of memory allocated for thebuffer. The buffer size may be resized to accommodate the specified timespan. If the addition of the drop detected at block 631 to the bufferwould induce a buffer overflow, at least one drop may be removed fromthe buffer. The buffer may be a first-in first-out (FIFO) buffer, sothat the removed drop is the least recent drop in the drop historybuffer. The buffer may be trimmed or expanded so that a specifiedmaximum or minimum number of drops are included in the history buffer.

At block 636 and block 643, a check is performed to insure minimumintervals are available for further determinations. For instance, if arolling drop rate average is to be determined, a check may be performedto insure that a minimum number of drops are included in the buffer. Insome embodiments, a check may be performed to insure that a minimum timebetween the most recent and least recent drops in the buffer exists. Insome embodiments, a check may be performed to insure that a minimum timebetween successive drops in the buffer exists. These and other checksmay be performed to insure the statistical significance or stability offurther determinations.

In some embodiments, a rolling average may be determined. In at leastone of the various embodiments, a rolling average may be based on aratio of a total number of detected drops in the buffer to a totalamount of time between the detections. For instance, a total amount oftime between the detections may be based on a difference of thedetection time of the most recent drop in the buffer and a detectiontime of the least recent drop in the buffer. In some embodiments, therolling average may be determined in various units. For instance, therolling average may be determined in drops per unit time, or timebetween drops. In at least one of the various embodiments, the rollingaverage may be determined in volume of fluid per unit time or time perunit of volume. It is to be understood that other methods fordetermining a rolling average may be employed.

If a user has indicated to measure the drop rate, then method 633proceeds to block 638. For instance, a user may indicate to measure thedrop rate by activating a measure mode through a user interface, such asuser interface 106 of FIGS. 1A and 1B. At block 638, the determinedrolling average may be displayed. Displaying the rolling average may beenabled by employing a display unit, such as display unit 102 of FIGS.1A and 1B.

If a user has not indicated to measure the drop rate, then method 633proceeds to block 640. At block 640, the most recent time interval maybe displayed. The most recent time interval may be based on at least thedetection times of the two most recent drops in the drop history buffer.

At decision block 644, a determination is performed based on at least adrip stability. The drip stability may be determined based on acomparison of a plurality of distances between detection times ofsuccessive drops included in the drop history buffer. If the dripstability is less than a predetermined threshold, method 641 proceeds toblock 648. An illustrative, but non-limiting or non-constraining valueof a stability threshold is a variation of 12.5%. At block 648, as withblock 640, the most recent time interval may be displayed. Otherwisemethods 641 proceeds to decision block 645.

At block 645, a determination is performed based on whether the drophistory buffer spans a predetermined length of time. If the buffer doesnot span the predetermined length of time, method 641 proceeds to block648. Otherwise, method 641 proceeds to decision block 646.

At block 646, a determination is performed based on whether the bufferhas a predetermined minimum threshold of intervals. If the buffer doesnot have the predetermined threshold of intervals, method 641 proceedsto block 648. Otherwise, method 641 proceeds to block 647. At block 647,the determined rolling average is displayed.

FIG. 7 shows one embodiment of device body 750 included in someembodiments of a monitoring device. Device body 750 may be opened andclosed. As shown in FIG. 7, device body 750 is an open state. At least aportion of device body 750 is enabled as a clip that can be opened bythe application of a force. Clip handles 752 may be actuated by anactuating force to open device body 750. Clip handles 752 may provideleverage for a user to provide the actuating force required to opendevice body 750. During an opening or closing operation, portions ofdevice body 750 may pivot about hinge 754.

When the actuating force is not applied to clip handles 752, device body750 may be in its closed state. Spring 756 may supply the force to closethe device. Device body 750 may include a first wing 760 and a secondwing 762. First wing 760 and second wing 762 may affixed about hinge754. First wing 760 may include a first trench 764. Second wing 762 mayinclude a second trench 766.

When device body 750 is in a closed state, first trench 764 and secondtrench 766 may be aligned to form a cavity, such as cavity 258 of FIG.2. When device body 750 is affixed to a drip chamber, such as dripchamber 292 of FIG. 2, at least a portion of the drip chamber may bereceived by the cavity formed by the alignment of first trench 764 andsecond trench 766. At least one of first trench 764 and second trench766 may include textured material to enable gripping of the dripchamber.

FIGS. 8A, 8B, and 8C show various views of embodiments of flow ratemonitoring device 800. Monitoring device 800 may include display unit802, user input interface 806, and user audio interface 808.

Monitoring device 800 may include a channel. Some embodiments mayinclude trench 864. When monitoring device 800 is affixed to a dripchamber, such a drip chamber 192 of FIG. 1, at least a portion of thedrip chamber may fit snuggly in trench 864. At least one inner surfaceof trench 864 may include textured material 868 to assist in grippingthe drip chamber. In some embodiments, at least one inner surface oftrench 864 may include camming device 870 to assist in gripping the dripchamber. In some embodiments, textured material 868 and camming device870 may be in opposition. In at least one embodiment, textured material868 may be a compressible material that expands and contracts toaccommodate drip chambers of various dimensions. In some embodiments,camming device 870 may be enabled to accommodate drip chambers ofvarious dimensions. Camming device 870 may include ridges or teeth thatenhance drip chamber gripping and friction.

Monitoring device 800 may include source 810. Source 810 may bepositioned along at least an inner surface of trench 864. Although notshown, monitoring device 800 may include a detector. Source 810 and thedetector may be in opposition along the inner surface of trench 864 toform an optical path across a drip chamber when monitoring device 800 isaffixed to the drip chamber.

In at least one of the various embodiments, the channel or trench 864may receive a portion of the drip chamber when monitoring device 800 isaffixed to the drip chamber. In some embodiments, because at least aportion of the channel or trench 864 is open, at least a portion of thedrip chamber is visible to a user during operation of monitoring device800. A user may be enabled to visually or manually inspect the droppingof the individual fluid drops during the monitoring of the fluid flowrate. Because at least a portion of the drip chamber is visible to theuser, some embodiments may provide the user with visual feedback of thedetected fluid drops. Due to visual feedback and in response to thedetermined fluid flow rate provided by the monitoring device, the usermay precisely adjust or vary the flow rate, such as a manual operationof a roller clamp, like roller clamp 196 off FIGS. 1A and 1B, or othersuch adjusting means, to achieve the desired target flow rate.

FIG. 8A shows monitoring device 800 from a front-side view from anoblique angle. FIG. 8B shows monitoring device 800 from a front view.FIG. 8C shows monitoring device 800 from a top view.

While the disclosure has been shown and described with respect tospecific embodiments thereof, this is for the purpose of illustrationrather than limitations, and other variations and modifications of thespecific embodiments herein shown and described will be apparent tothose skilled in the art within the intended spirit and scope of thedisclosure as set forth in the appended claims.

While the preferred embodiment of the disclosure has been illustratedand described, as noted above, many changes can be made withoutdeparting from the spirit and scope of the disclosure. Accordingly, thescope of the disclosure is not limited by the disclosure of thepreferred embodiment. Instead, the disclosure should be determinedentirely by reference to the claims that follow.

What is claimed is:
 1. A flow rate monitoring device for monitoring aflow rate of fluid through a drip chamber, the device comprising: (a) asource enabled to emit electromagnetic radiation (EMR); (b) a detectorenabled to generate a detector signal; (c) a device body configured andarranged to position the source and the detector about at least oneouter surface of the drip chamber such that the source and the detectordefine an optical path across the drip chamber, wherein fluid betweenthe source and the detector inhibits EMR travelling along the opticalpath; and (d) a processor device that executes instructions that performactions, comprising: i. detecting a fluid drop based on at least adifference between a plurality of detector signal values temporallyseparated by a predetermined lag time; and ii. determining the flow rateof fluid based on at least a predetermined drip factor and detecting aplurality of fluid drops.
 2. The flow rate monitoring device of claim 1,wherein detecting the fluid drop is further based on a comparison of aplurality of temporally ordered difference values, wherein each of theplurality of difference values correspond to differences in theplurality of detector signals that are temporally separated by the lagtime.
 3. The flow rate monitoring device of claim 1, wherein the actionsfurther include vetoing a detection of a second fluid drop when atemporal difference between the detection of the second fluid drop and adetection of a first fluid drop is less than a predetermined lockouttime.
 4. The flow rate monitoring device of claim 1, wherein detectingthe fluid drop further comprises: (a) generating a drop waveform basedon detector signal values sampled at a plurality of temporally orderedtimes, wherein the drop waveform is modulated by the fluid drop; (b)generating a lag time difference waveform based on at least the lag timeand a plurality of differences of the drop waveform corresponding todifferent times; and (c) detecting the fluid drop based on at least asignal included in the lag time difference waveform.
 5. The flow ratemonitoring device of claim 1, wherein the source is a light emittingdiode (LED).
 6. The flow rate monitoring device of claim 1, wherein thedetector is a photodiode.
 7. The flow rate monitoring device of claim 1,wherein the source is further enabled to emit EMR within a wavelengthwindow, wherein wavelengths within the wavelength window are longer thanvisible light wavelengths and a sensitivity of the detector is greaterfor at least a portion of the wavelengths within the wavelength windowthan for visible light wavelengths.
 8. The flow rate monitoring deviceof claim 1, wherein the actions further include: (a) detecting a firstfluid drop at a first detection time; (b) adding the first detectiontime to a drop history buffer, wherein the drop history buffer includesat least a plurality of other detection times and each of the otherdetection times corresponds to a previously detected fluid drop; (c)removing at least one of the other detection times from the drop historybuffer; and (d) determining an average drop rate based on at least thedetection times included in the history buffer.
 9. The flow ratemonitoring device of claim 8, wherein the actions further include: (a)determining a drip stability based on a comparison of a plurality oftemporal distances between the detection times included in the drophistory buffer.
 10. The flow rate monitoring device of claim 1, whereinthe actions further include at least one of: (a) displaying the flowrate of fluid; (b) providing an alert when the flow rate of fluid isoutside of a predetermined range; (c) providing an alert when a dripstability is less than a predetermined threshold; and (d) providing analert when an average drop rate is outside of another predeterminedrange.
 11. The flow rate monitoring device of claim 1, wherein thedevice body includes a clip configured and arranged for at least aclosed state, wherein the closed state forms a cavity within the devicebody, wherein the source and detector are in opposition along at leastone inner surface of the cavity such that the cavity may receive atleast a portion of the drip chamber forming the optical path across thedrip chamber.
 12. The flow rate monitoring device of claim 11, whereinat least a portion of the inner surface of the cavity includes atextured feature for producing friction between the inner surface of thecavity and the outer surface of the drip chamber.
 13. The flow ratemonitoring device of claim 1, wherein the device body includes a trench,wherein the source and detector are in opposition along at least oneinner surface of the trench and the trench is configured and arrangedfor affixing the device to the drip chamber such that at least a portionof the drip chamber is visible to a user, providing visual feedback ofthe detected fluid drops.
 14. The flow rate monitoring device of claim13, wherein the at least one inner surface of the trench includes atleast one of: (a) a textured portion; (b) a gripping cam; and (c) acompressible gripping material.
 15. The flow rate monitoring device ofclaim 1, wherein the device further includes a battery.
 16. The flowrate monitoring device of claim 1, wherein power to at least one of thedetector and the source is pulsed.
 17. A method for monitoring a flowrate of fluid through a drip chamber, the method comprising actions of:(a) positioning a source and a detector about at least one outer surfaceof the drip chamber such that the source and the detector define anoptical path across the drip chamber, wherein the source is enabled toemit electromagnetic radiation (EMR) and the detector is enabled togenerate a detector signal, and wherein fluid between the source and thedetector inhibits EMR travelling along the optical path; (b) detecting afluid drop based on at least a difference between a plurality ofdetector signal values temporally separated by a predetermined lag time;and (c) determining the flow rate of fluid based on at least apredetermined drip factor and detecting a plurality of fluid drops. 18.The method of claim 17, wherein detecting the fluid drop is furtherbased on a comparison of a plurality of temporally ordered differencevalues, wherein each of the plurality of difference values correspond todifferences in the plurality of detector signals that are temporallyseparated by the lag time.
 19. The method of claim 17, wherein theactions further include vetoing a detection of a second fluid drop whena temporal difference between the detection of the second fluid drop anda detection of a first fluid drop is less than a predetermined lockouttime.
 20. The method of claim 17, wherein detecting the fluid dropfurther includes: (a) generating a drop waveform based on detectorsignal values sampled at a plurality of temporally ordered times,wherein the drop waveform is modulated by the fluid drop; (b) generatinga lag time difference waveform based on at least the lag time and aplurality of differences of the drop waveform corresponding to differenttimes; and (c) detecting the fluid drop based on at least a signalincluded in the lag time difference waveform.
 21. The method of claim17, wherein the source is a light emitting diode (LED).
 22. The methodof claim 17, wherein the detector is a photodiode.
 23. The method ofclaim 17, wherein the source is further enabled to emit EMR within awavelength window, wherein wavelengths within the wavelength window arelonger than visible light wavelengths and a sensitivity of the detectoris greater for at least a portion of the wavelengths within thewavelength window than for visible light wavelengths.
 24. The method ofclaim 17, wherein the actions further include: (a) detecting a firstfluid drop at a first detection time; (b) adding the first detectiontime to a drop history buffer, wherein the drop history buffer includesat least a plurality of other detection times and each of the otherdetection times corresponds to a previously detected fluid drop; (c)removing at least one of the other detection times from the drop historybuffer; and (d) determining an average drop rate based on at least thedetection times included in the history buffer.
 25. The method of claim24, wherein the actions further include: (a) determining a dripstability based on a comparison of a plurality of temporal distancesbetween the detection times included in the drop history buffer.
 26. Themethod of claim 24, wherein the actions further include at least one of:(a) displaying the flow rate of fluid; (b) providing an alert when theflow rate of fluid is outside of a predetermined range; (c) providing analert when a drip stability is less than a predetermined threshold; and(d) providing an alert when an average drop rate is outside of anotherpredetermined range.
 27. The method of claim 17, wherein the source andthe detector are positioned such that at least a portion of the dripchamber is visible to a user, providing visual feedback of the detectedfluid drops.
 28. A system for monitoring a flow rate of fluid through adrip chamber, the system comprising: (a) a monitoring device comprising:i. a source enabled to emit electromagnetic radiation (EMR); ii. adetector enabled to generate a detector signal; and iii. a device bodyconfigured and arranged to position the source and the detector about atleast one outer surface of the drip chamber such that the source and thedetector define an optical path across the drip chamber, wherein fluidbetween the source and the detector inhibits EMR travelling along theoptical path; and (b) a processor device that executes instructions thatperform actions, comprising: i. detecting a fluid drop based on at leasta difference between a plurality of detector signal values temporallyseparated by a predetermined lag time; and ii. determining the flow rateof fluid based on at least a predetermined drip factor and detecting aplurality of fluid drops.
 29. The system of claim 28, wherein detectingthe fluid drop is further based on a comparison of a plurality oftemporally ordered difference values, wherein each of the plurality ofdifference values correspond to differences in the plurality of detectorsignals that are temporally separated by the lag time.
 30. The system ofclaim 29, wherein the actions further include vetoing a detection of asecond fluid drop when a temporal difference between the detection ofthe second fluid drop and a detection of a first fluid drop is less thana predetermined lockout time.
 31. The system of claim 28, wherein thesource and the detector are positioned such that at least a portion ofthe drip chamber is visible to a user, providing visual feedback of thedetected fluid drops.
 32. The system of claim 28, wherein detecting thefluid drop further includes: (a) generating a drop waveform based ondetector signal values sampled at a plurality of temporally orderedtimes, wherein the drop waveform is modulated by the fluid drop; (b)generating a lag time difference waveform based on at least the lag timeand a plurality of differences of the drop waveform corresponding todifferent times; and (c) detecting the fluid drop based on at least asignal included in the lag time difference waveform.